diff --git a/build.zig.zon b/build.zig.zon
index 3fcf39a..de5eaae 100644
--- a/build.zig.zon
+++ b/build.zig.zon
@@ -3,7 +3,7 @@
     .version = "0.4.0",
     .fingerprint = 0xdc70f8287a69c300,
 
-    .minimum_zig_version = "0.15.0",
+    .minimum_zig_version = "0.16.0-dev.2145+ec25b1384",
 
     .dependencies = .{},
 
diff --git a/demo/debug.zig b/demo/debug.zig
index eeda369..b55e44c 100644
--- a/demo/debug.zig
+++ b/demo/debug.zig
@@ -9,7 +9,7 @@ pub fn main() void {
 }
 
 fn handler(ctx: lambda.Context, event: []const u8) ![]const u8 {
-    var str: std.io.Writer.Allocating = try .initCapacity(ctx.arena, 1024);
+    var str: std.Io.Writer.Allocating = try .initCapacity(ctx.arena, 1024);
 
     const cfg = ctx.config;
     try str.writer.print(
diff --git a/demo/url_buffer.zig b/demo/url_buffer.zig
index e338fc8..de41980 100644
--- a/demo/url_buffer.zig
+++ b/demo/url_buffer.zig
@@ -90,7 +90,7 @@ fn homePage(ctx: lambda.Context) ![]const u8 {
 /// The `url.Request` contains both the HTTP request and additional AWS metadata.
 fn ipAddrPage(ctx: lambda.Context, req: lambda.url.Request) ![]const u8 {
     // Generate dynamic HTML content, note the usage of an arena allocator.
-    var html: std.io.Writer.Allocating = .init(ctx.arena);
+    var html: std.Io.Writer.Allocating = .init(ctx.arena);
 
     try html.writer.writeAll(global_nav);
     if (req.request_context.http.source_ip) |addr| {
@@ -110,7 +110,7 @@ fn ipAddrPage(ctx: lambda.Context, req: lambda.url.Request) ![]const u8 {
 
 /// Use a parsed query parameter provided by the decoded request to greet the user.
 fn greetPage(ctx: lambda.Context, req: lambda.url.Request) ![]const u8 {
-    var html: std.io.Writer.Allocating = .init(ctx.arena);
+    var html: std.Io.Writer.Allocating = .init(ctx.arena);
 
     try html.writer.writeAll(global_nav);
 
@@ -165,7 +165,7 @@ fn storagePage(ctx: lambda.Context, req: lambda.url.Request) ![]const u8 {
         }
 
         // Encode the cookie value
-        var new_cookie: std.io.Writer.Allocating = .init(ctx.arena);
+        var new_cookie: std.Io.Writer.Allocating = .init(ctx.arena);
         errdefer new_cookie.deinit();
         try new_cookie.writer.writeAll("store=");
         try std.base64.standard.Encoder.encodeWriter(&new_cookie.writer, value);
@@ -176,7 +176,7 @@ fn storagePage(ctx: lambda.Context, req: lambda.url.Request) ![]const u8 {
     }
 
     // Render a form to display and update the stored value.
-    var html: std.io.Writer.Allocating = .init(ctx.arena);
+    var html: std.Io.Writer.Allocating = .init(ctx.arena);
     try html.writer.writeAll(global_nav);
     try html.writer.print(
         \\<form>
diff --git a/src/event/url.zig b/src/event/url.zig
index eb0b7b7..36e5df5 100644
--- a/src/event/url.zig
+++ b/src/event/url.zig
@@ -46,7 +46,7 @@ pub const Response = struct {
     pub const internal_server_error = "{\"statusCode\":500,body:\"Internal Server Error\"}";
 
     pub fn encode(self: Response, gpa: Allocator) ![]const u8 {
-        var buffer: std.io.Writer.Allocating = .init(gpa);
+        var buffer: std.Io.Writer.Allocating = .init(gpa);
         errdefer buffer.deinit();
 
         try buffer.writer.writeByte('{');
@@ -156,7 +156,7 @@ test Response {
 ///     .body = .{ .textual = "<h1>Incoming...</h1>" },
 /// });
 /// ```
-pub fn openStream(ctx: hdl.Context, stream: hdl.Stream, response: Response) !*std.io.Writer {
+pub fn openStream(ctx: hdl.Context, stream: hdl.Stream, response: Response) !*std.Io.Writer {
     // https://github.com/awslabs/aws-lambda-rust-runtime/blob/main/lambda-runtime/src/requests.rs
     // https://aws.amazon.com/blogs/compute/using-response-streaming-with-aws-lambda-web-adapter-to-optimize-performance
     const writer = try stream.openPrint(INTEGRATION_CONTENT_TYPE, "{f}", .{StreamingResponse{
@@ -183,12 +183,12 @@ const StreamingResponse = struct {
     arena: Allocator,
     response: Response,
 
-    pub fn format(self: @This(), writer: *std.io.Writer) !void {
+    pub fn format(self: @This(), writer: *std.Io.Writer) !void {
         var response = self.response;
         response.body = .{ .textual = "" };
 
         const prelude = response.encode(self.arena) catch {
-            return std.io.Writer.Error.WriteFailed;
+            return std.Io.Writer.Error.WriteFailed;
         };
         try writer.writeAll(prelude);
     }
diff --git a/src/runtime/api.zig b/src/runtime/api.zig
index b12ea34..167e6a7 100644
--- a/src/runtime/api.zig
+++ b/src/runtime/api.zig
@@ -205,7 +205,7 @@ fn sendRequest(arena: Allocator, client: *Client, path: []const u8, payload: ?[]
 }
 
 fn formatError(arena: Allocator, err_category: []const u8, err: ErrorRequest) ![]const u8 {
-    var buffer: std.io.Writer.Allocating = .init(arena);
+    var buffer: std.Io.Writer.Allocating = .init(arena);
 
     try buffer.writer.print(
         \\{{"errorType":"{s}.
diff --git a/src/runtime/context.zig b/src/runtime/context.zig
index 1110c73..30fe7e5 100644
--- a/src/runtime/context.zig
+++ b/src/runtime/context.zig
@@ -19,7 +19,7 @@ pub const Context = struct {
     config: ConfigMeta = .{},
     /// Request metadata of the invocation.
     request: RequestMeta = .{},
-
+    io: *const std.Io,
     _force_destroy: *bool,
     _kv: *const std.process.EnvMap = undefined,
 
diff --git a/src/runtime/handle.zig b/src/runtime/handle.zig
index 82a3318..34368f6 100644
--- a/src/runtime/handle.zig
+++ b/src/runtime/handle.zig
@@ -98,7 +98,7 @@ pub const Stream = struct {
     };
 
     /// Start streaming a response of a specified content type.
-    pub fn open(self: @This(), content_type: []const u8) !*std.io.Writer {
+    pub fn open(self: @This(), content_type: []const u8) !*std.Io.Writer {
         return self.openPrint(content_type, "", {});
     }
 
@@ -111,7 +111,7 @@ pub const Stream = struct {
         content_type: []const u8,
         comptime prelude_fmt: []const u8,
         prelude_args: anytype,
-    ) !*std.io.Writer {
+    ) !*std.Io.Writer {
         if (self.state.* != .pending) return error.ReopeningStream;
 
         std.debug.assert(content_type.len > 0);
diff --git a/src/runtime/serve.zig b/src/runtime/serve.zig
index 76450e1..5bac1ff 100644
--- a/src/runtime/serve.zig
+++ b/src/runtime/serve.zig
@@ -20,6 +20,8 @@ pub const Options = struct {};
 pub const Server = struct {
     gpa: std.heap.GeneralPurposeAllocator(.{}),
     arena: std.heap.ArenaAllocator,
+    threaded: std.Io.Threaded,
+    io: std.Io,
     http: HttpClient,
     env: std.process.EnvMap,
     request_id: []const u8 = "",
@@ -48,7 +50,13 @@ pub const Server = struct {
             return initFailed(arena_alloc, null, error.MissingRuntimeOrigin, "Missing the runtime’s API origin URL");
         };
 
-        self.http = HttpClient.init(gpa_alloc, api_origin) catch |err| {
+        // Initialize threaded IO - owned by Server
+        self.threaded = std.Io.Threaded.init(gpa_alloc, .{});
+        errdefer self.threaded.deinit();
+
+        self.io = self.threaded.io();
+
+        HttpClient.init(&self.http, gpa_alloc, api_origin, self.io) catch |err| {
             return initFailed(arena_alloc, null, err, "Creating a HTTP client failed");
         };
     }
@@ -57,6 +65,7 @@ pub const Server = struct {
         self.http.deinit();
         self.env.deinit();
         self.arena.deinit();
+        self.threaded.deinit();
 
         switch (self.gpa.deinit()) {
             .ok => {},
@@ -98,6 +107,7 @@ pub const Server = struct {
             .gpa = self.gpa.allocator(),
             .arena = self.arena.allocator(),
             ._force_destroy = &force_terminate,
+            .io = &self.io,
         };
         ctx.loadMeta(&context, &self.env);
 
@@ -134,8 +144,8 @@ pub const Server = struct {
     }
 
     pub fn respondFailure(self: *Server, err: anyerror, trace: ?*std.builtin.StackTrace) !void {
-        if (trace) |t| {
-            log.err("The handler returned an error `{s}`.{f}", .{ @errorName(err), t });
+        if (trace) |_| {
+            log.err("The handler returned an error `{s}`.", .{@errorName(err)});
         } else {
             log.err("The handler returned an error `{s}`.", .{@errorName(err)});
         }
@@ -203,7 +213,7 @@ pub const Server = struct {
         body: std.http.BodyWriter,
         arena: std.mem.Allocator,
 
-        pub fn writer(self: *Stream) *std.io.Writer {
+        pub fn writer(self: *Stream) *std.Io.Writer {
             return &self.body.writer;
         }
 
diff --git a/src/utils/Http.zig b/src/utils/Http.zig
index f60e2b2..3895b07 100644
--- a/src/utils/Http.zig
+++ b/src/utils/Http.zig
@@ -2,6 +2,8 @@
 const std = @import("std");
 const testing = std.testing;
 const Client = std.http.Client;
+const Io = std.Io;
+const Threaded = std.Io.Threaded;
 const Allocator = std.mem.Allocator;
 const builtin = @import("builtin");
 const package_version = @import("meta.zig").package_version;
@@ -20,9 +22,9 @@ const USER_AGENT = std.fmt.comptimePrint(
 client: Client,
 uri: std.Uri,
 
-pub fn init(gpa: Allocator, origin: []const u8) !Self {
+pub fn init(self: *Self, gpa: Allocator, origin: []const u8, io: Io) !void {
     const idx = std.mem.indexOfScalar(u8, origin, ':');
-    const uri = std.Uri{
+    self.uri = std.Uri{
         .path = .{ .percent_encoded = "" },
         .scheme = "http",
         .host = .{ .raw = if (idx) |i| origin[0..i] else origin },
@@ -32,10 +34,7 @@ pub fn init(gpa: Allocator, origin: []const u8) !Self {
             null,
     };
 
-    return .{
-        .client = Client{ .allocator = gpa },
-        .uri = uri,
-    };
+    self.client = Client{ .allocator = gpa, .io = io };
 }
 
 pub fn deinit(self: *Self) void {
@@ -137,7 +136,7 @@ fn parseResponse(arena: Allocator, res: *Client.Response) !Result {
     var transfer_buffer: [64]u8 = undefined;
     const reader = res.reader(&transfer_buffer);
 
-    var buffer: std.io.Writer.Allocating = .init(arena);
+    var buffer: std.Io.Writer.Allocating = .init(arena);
     _ = reader.streamRemaining(&buffer.writer) catch |err| switch (err) {
         error.ReadFailed => return res.bodyErr().?,
         else => |e| return e,
diff --git a/src/utils/environ.zig b/src/utils/environ.zig
index 62769da..891299b 100644
--- a/src/utils/environ.zig
+++ b/src/utils/environ.zig
@@ -21,5 +21,5 @@ fn parseAndPutVar(map: *std.process.EnvMap, line: [*]u8) !void {
     while (line[end_i] != 0) : (end_i += 1) {}
     const value = line[line_i + 1 .. end_i];
 
-    try map.putMove(key, value);
+    try map.put(key, value);
 }